Ideofact has a couple of interesting posts (here and here) on the so-called Beaker Culture of central Europe and the fact that "these people left us no name by which to call them".

That reminded me of something that happened to me in grad school. In my reading I ran across the German term 'Urdummheit' and immediately thought "'primeval stupidity', that's an amusingly un-P.C. concept". On second thought, I decided I was probably mistaken. Since English is a Germanic language, surely German 'dumm' is related to the oldest sense of English 'dumb' and means 'mute' (as in 'deaf and dumb') rather than 'stupid'. 'Primeval muteness' would be a very useful concept, referring to what Ideofact is talking about, the fact that many preliterate societies leave us a great deal of information about them, but nothing that would tell us even the names of their tribes or their kings or anything else. I had just about convinced myself that that was the meaning of 'Urdummheit' when I decided to look it up in a German dictionary, just to make sure. It means 'primeval stupidity'.